问使用浮动将元素放在带有CSS的右侧

EN

nav {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100px;
  padding: 10px 100px;
  z-index: 500;
  box-sizing: content-box;
  transition: .3s;
  background: red;
}

nav.white {
  background: white;
  height: 35px;
  padding: 10px 100px;
  transition: .5s;
}

nav ul {
  list-style: none;
  float: left;
  margin: 0;
  padding: 0;
  display: flex;
  width: 90%;
   position: relative;
}

nav ul li {
  list-style: none;
}

nav ul li:last-child {
  display: inline-block;
    right: 5%;
    position: absolute;
    top: 0;
}

nav ul li a {
  line-height: 80px;
  color: #FFFFFF;
  margin: 12px 30px;
  text-decoration: none;
  text-transform: capitalize;
  transition: .5s;
  padding: 10px 5px;
  font-size: 16px;
}

nav ul li a:hover {
  background-color: rgba(255,255,255,0.2);
}


nav.white ul li a {
  color: #000;
  line-height: 40px;
  transition: .5s;
}

nav ul li a:focus {
  outline: none;
}

    <div class="wrapper">
      <nav>
        <ul>
          <li><a href="#">LOGO</a></li>
          <li><a href="#">Home</a></li>
          <li><a href="#">Page 1</a></li>
          <li><a href="#">Page 2</a></li>
          <li><a class="contact" href="#">Contact</a></li>
        </ul>
      </nav>

nav ul li a {
  float: left;
}

nav ul li a.contact {
  float: right;
}

.wrapper li {list-style-type: none;}
.wrapper {
  overflow: hidden;
  background-color: red;
}
.wrapper .logo{
  margin-right : 30px;
}
.wrapper a {
  float: left;
  color: #f2f2f2;
  text-align: center;
  padding: 14px 16px;
  text-decoration: none;
  font-size: 17px;
}

.wrapper a:hover {
  background-color: #ddd;
  color: black;
}

.wrapper a.active {
  background-color: #4CAF50;
  color: white;
}

.topnav-right {
  float: right;
}

<div class="wrapper">
  <a class="active logo" href="#">Logo</a>
  <a href="#">Home</a>
  <a href="#">Page 1</a>
  <a href="#">Page 2</a>
  <div class="topnav-right">
    <li><a class="contact" href="#">Contact</a></li>
  </div>
</div>